Cellular

Energetics

Photosynthesis, Cellular Respiration and

Fermentation

TEKS

B.4 Science concepts. The student knows that cells are the basic structures of all living things

with specialized parts that perform specific functions and that viruses are different from cells.

The student is expected to:

B.4B investigate and explain cellular processes, including homeostasis, energy conversions, transport

of molecules, and synthesis of new molecules

B.9 Science concepts. The student knows the significance of various molecules involved in

metabolic processes and energy conversions that occur in living organisms. The student is

expected to:

B.9B compare the reactants and products of photosynthesis and cellular respiration in terms of energy

and matter;

Vocabulary

• Chemical Reaction

• Reactant

• Product

• Photosynthesis

• Autotroph

• Producer

• Chloroplast

• Light Dependent Reaction

• Calvin Cycle

• Cellular Respiration

• Heterotroph

• Consumer

• Adenosine Triphosphate (ATP)

• Mitochondria

• Glycolysis

• Krebs/Citric Acid cycle

• ETC (Oxydative Phosphorylation)

• Fermentation

• Endosymbiotic Theory

Essential Question

• How do energy and matter flow through the processes of

photosynthesis and cellular respiration?

How organisms get energy

1. Autotrophs: able to produce own glucose

– Ex: plants, algae, cyanobacteria

– Also called: producers

2. Heterotrophs: must take in glucose from outside source

– Ex: animals, fungus, most bacteria, protozoans

– Also called: consumers

Why is food so important?• The energy from carbon based molecules (food) is

needed to re-charge ADP (adenosine di-phosphate) to

ATP (adenosine tri-phosphate) molecules

• ATP provides energy for ALL metabolic reactions.

Adenine Ribose 3 Phosphate groups

Adenosine

ADP and ATP• To get energy out of ATP, the bond

between the last two phosphate groups is

broken.

ADP ATP

Energy

EnergyAdenosine diphosphate (ADP) + Phosphate Adenosine triphosphate (ATP)

Partiallychargedbattery

Fullychargedbattery

Importance of energy

• Cells need energy to be able to carry out important

metabolic functions to sustain life.

– Ex: Active transport, cell division, movement of flagella

or cilia, and the production, transport, and storage of

proteins

Photosynthesis

• The process autotrophs use to make glucose sugars from

carbon dioxide, water, and light energy

Photosynthesis and Respiration are

complementary cycles

6CO2 + 6H2O → C6H12O6 + 6O2

C6H12O6 + 6O2 → 6CO2 + 6H2O

Energy in

Sunlight

Energy out

ATP

Enzymes

Enzymes

Where and how are sugars made?Light Energy

Chloroplast

CO2 + H2O Sugars + O2

Pigments

• Chlorophyll is a pigment, a

molecule that can absorb light

energy.

• Unused light is reflected.

• What is the color of the wavelength

least used by chlorophyll?

Absorption of Light byChlorophyll a and Chlorophyll b

V B G YO R

Chlorophyll b

Chlorophyll a

Photosynthesis is an endergonic

reaction…”energy in”

1. Light dependent reaction

2. Calvin cycle

ChloroplastLight

Sugars

CO2

Light-Dependent Reactions

CalvinCycle

NADPH

ATP

ADP + P

NADP+

Chloroplast

H20

O2

Step 1: Light dependent reaction

Hydrogen

Ion MovementPhotosystem II

Inner

Thylakoid

Space

Thylakoid

Membrane

Stroma

ATP synthase

Electron

Transport ChainPhotosystem I ATP Formation

Chloroplast

STROMA(low H concentration)

STROMA(low H concentration)

THYLAKOID SPACE(high H concentration)

Light

Photosystem II

Cytochromecomplex

Photosystem ILight

NADP

reductase

NADP + H

ToCalvinCycle

ATPsynthase

Thylakoidmembrane

2

1

3

NADPH

Fd

Pc

Pq

4 H+

4 H++2 H+

H+

ADP

+

P i

ATP

1/2

H2OO2

Light dependent reaction

• Pigments (chlorophyll) inside of the chloroplasts are arranged

into photosystems (PS II and PS I).

• Photosystems absorb sunlight.

• Electrons become energized and help to produce ATP &

NADPH.

Step 1: Light

Dependent reactions

• location:

grana of chloroplast

• Photosystem II:

– energized chlorophyll splits water into

Oxygen (released) and Hydrogen (carried by

NADP to be used later)

• Photosystem I:

– energized chlorophyll makes ATP (to be

used later)

Light Dependent reactions

• The products of the light reactions will move on to

the Calvin cycle:

• ATP

• NADPH

Step 2: Calvin cycle

ChloropIast

CO2 Enters the Cycle

Energy Input

5-Carbon

Molecules

Regenerated

Sugars and other compounds

6-Carbon Sugar

Produced

Calvin Cycle

• Location: stroma (fluid) of chloroplast

• CO2 is “fixed” meaning it is attached to other molecules in the stroma.

Eventually sugar molecules are released from the cycle.

• Products: Glucose (sugar/food) is made (from 6 turns of cycle)

6CO2 + 6H2O C6H12O6 + 6O2

Calvin cycle

• ATP and NADPH supply the

energy needed to change the

CO2 taken in by plants into a

6 carbon sugar molecule.

glucose

What happens to the sugar?

• Plants can store the sugar in roots or stems (ex: potatoes,

turnips, carrots, sugar cane)

• Heterotrophs such as humans must eat or consume

foods (ex. Carrots, potatoes, etc.) in order to make ATP

by cellular respiration.

• Sugars & starches are used to make ATP by cellular

respiration as needed.

• ALL living organisms need and use

energy.

• Therefore ALL organisms need ATP

• ALL organisms (plants and animals,

fungi, bacteria and protists) re-charge

their ADP into ATP through respiration

Cellular Respiration

• The process autotrophs and heterotrophs use to break

down glucose (energetic molecules) to make ATP

Photosynthesis and Respiration are

complementary cycles

6CO2 + 6H2O → C6H12O6 + 6O2

C6H12O6 + 6O2 → 6CO2 + 6H2O

Energy in

Sunlight

Energy out

ATP

Enzymes

Enzymes

Two types of respiration

• Aerobic respiration: Organisms that require oxygen use aerobic respiration to make ATP but switch to fermentation when oxygen is not available.

• Anaerobic respiration: Organisms that live without oxygen use anaerobic respiration to make ATP and die in the presence of oxygen.

Where cell respiration takes place

• Prokaryotes: cell

membrane (don’t have mitochondria)

• Eukaryotes:

mitochondria

organelle

Steps of aerobic respiration1. Glycolysis

2. Krebs cycle

3.1 Electron transport chain

3.2 ATP synthase (Oxidative Phosphorylation)

Step 1: Glycolysis

• Glucose molecules are broken down into two molecules

of pyruvic acid.

Glucose

To the electron

transport chain

2 Pyruvic acid

– Location: cytoplasm (outside mitochondria)

• Anaerobic stage (occurs without oxygen)

– Glucose (6C) is split into two Pyruvates (3C) by the force of 2

ATP molecules

– Products: Hydrogen is saved by NAD+ to be used later & 4

ATP (net gain of 2) are produced

GLYCOLYSIS

Step 2: Krebs or Citric Acid cycle

• Pyruvates are altered to

produce NADH and

FADH2, electron

carriers.

• CO2 is created here

Citric Acid

Production

• Location: mitochondria (fluid

matrix)

• Carbon compounds join & break

apart several times during the

cycle, releasing lots of CO2

• Products: small amount of ATP

& large amount of NADH and

FADH2 (used later)

Krebs Cycle

Step 3: Oxidative Phosphorylation

Electron Transport

Hydrogen Ion Movement

ATP Production

ATP synthase

Channel

Inner Membrane

Matrix

Intermembrane Space

Proteincomplexof electroncarriers

(carrying electronsfrom food)

Electron transport chain

Oxidative phosphorylation

Chemiosmosis

ATPsynth-ase

I

II

III

IVQ

Cyt c

FADFADH2

NADH ADP P iNAD

H

2 H + 1/2O2

H

HH

21

H

H2O

ATP

• Location: mitochondria (cristae,

inner membrane)

• Energy from Hydrogen atom’s

electrons is utilized to change

ADP into ATP

• Hydrogen ions (H+) ultimately

joins oxygen to make water as a

waste product

Electron transport chain (ETC) &

Oxidative Phosphorylation

Electron transport chain

• NADH and FADH2 supplies the electron needed to start the ETC.

• Hydrogen ions (protons) are pumped into the inner membrane space.

• The protons flow through the ATP-making enzyme (ATP synthase), activating the enzyme to add a phosphate group to ADP to make ATP.

What happens if there is no oxygen available and the

organism is aerobic?

1. Glycolysis

2. Fermentation: lactic acid or alcohol

Glucose Pyruvic acid

Fermentation

• The process of making a little ATP without the presence

of Oxygen.

Alcoholic Fermentation

(anaerobic respiration)

• Without enough oxygen

present, an “alternate route” is

taken, producing other

products & much less ATP

• In yeast: Alcohol and CO2

are produced

• Ex: in bread-making & the

alcohol industry

Alcohol industry

• Yeast undergo alcohol

fermentation when they do not

have oxygen to make ATP.

• The alcohol industry uses specific

yeast to convert fruit sugars into

alcohol.

Lactic Acid Fermentation

(anaerobic respiration)

• Without enough oxygen

present, an “alternate route” is

taken, producing other products

& much less ATP

• In muscles:

lactate is produced

• Causes sore muscles

Sore muscles• When a person exercises, the

muscle cells use up oxygen faster

than a person can breathe in.

• The muscle cells need O2 to make

ATP.

• The cells perform lactic acid

fermentation instead producing

lactic acid in the cells and when in

higher concentrations, makes

muscles feel sore.

US Swim Team members 2004

Endosymbiotic Theory

• Lynn Margulis proposed that

certain organelles evolved from a

symbiotic relationship between a

host cell and early prokaryotes.

This is supported by observation

& data.

• Mitochondria were

chemosynthetic aerobic

prokaryotes

• Chloroplasts were

photosynthetic prokaryotes